1994 Ferrari F355 3.5L Petrol · 355 NNU

The F355's 3.5-litre V8 is an interference engine, and Ferrari requires the cam belts, tensioners and ancillary services to be renewed every three years or 30,000 miles, regardless of how few miles the car has covered. Because the engine and transaxle must be removed to access the belts, the job is labour-intensive and easily deferred. A snapped belt causes piston-to-valve contact and catastrophic engine failure, so cars without a documented belt change within the interval are a major risk.

The factory F355 exhaust manifolds are thin-walled and prone to cracking with heat cycling, typically becoming apparent from around 25,000 to 40,000 miles. Cracks leak exhaust gases and, if ignored, can draw white residue into the engine bay and damage nearby components; once one side fails, the other usually follows shortly after. A ticking or exhaust-leak noise on cold start that fades as the engine warms is the classic warning. Replacement with original-pattern parts is expensive, so many cars have already been fitted with aftermarket headers.

The F355's 40-valve V8 uses valve guides that can wear, allowing oil into the combustion chambers and causing poor compression and oil burning. Ferrari estimated around a fifth of 1995 model-year cars could be affected, and a suspect batch also appeared in 1997–1998 cars, so the fault is not confined to very early examples. Blue smoke on overrun, oily spark plugs and a compression test reveal the problem, and renewing the guides requires cylinder-head work.

On Berlinetta and GTS (targa) models, the seam where the rear buttresses meet the rear wings flexes over time and cracks, admitting moisture between the aluminium and steel panels. Corrosion can be extensive under the paint and is often only revealed during a respray. Most cars show some degree of cracking in this area. Inspect the buttress-to-wing joints, rear wings and sills with a torch, and ask whether any repairs have been carried out.